The invention relates to medication injecting device assemblies and specifically to a pre-filled ampule for use with a hypodermic injection device which injects medication but which does not require piercing the skin of a patient with a hypodermic needle.
The medication ampules used with powered hypodermic devices are generally formed of high-strength plastic material which are capable of withstanding the pressures, generally in the vicinity of 8000 psi, which are utilized to inject medication through the skin of a patient without piercing the skin of the patient with a hypodermic needle. The ampules, or syringes, have sidewalls which are considerably heavier than those of conventional syringes and are usually formed of a plastomer material. A problem with the use of such plastics, such as polycarbonate, is that the plastic will react with, or diffuse into, the medication which is to be administered should the medication be present in the ampule for an extended period of time. This is particularly important in the case where it is desired to provide a patient with a pre-filled ampule which contains a precise measurement of medication. Such an ampule must be capable of being stored with the medication contained therein for an extended period of time yet must not contaminate the stored medication.
Injectable medication is usually stored in glass containers because glass is generally inert with respect to injectable medications and will not contaminate the stored medication stored therein. The provision of a glass ampule would therefore eliminate the problem of contamination if the medication is stored within the ampule for an extended period of time. However, a glass ampule would be required to have an unreasonably thick sidewall in order to withstand the pressures imparted thereto by the powered hypodermic device which is used in conjunction with the ampule.
Powered hypodermic devices are known which provide one or more gas charges to deliver injections by non-invasive hypodermic means. Generally, the smaller powered hypodermic devices, which are intended for use by patient self-administered medication, are one-shot devices in that a new gas charge containing cartridge must be provided for each injection. Larger devices are known which provide multiple injections from a single gas charge, but these devices are generally quite large and too expensive for patient-administration of medication. It is particularly important that patients who self-administer medication know how many times the device has been used on a given charge, so that the patient will not attempt to administer medication when the device does not have sufficient gas charge therein to provide a complete injection of the medication.
An object of the instant invention is to provide a pre-filled ampule for a powered-hypodermic injection device which will provide extended storage of medication therein without contamination of the medication by the material from which the ampule is formed.
Another object of the instant invention is to provide a medication holder formed of inert material which is capable of sustaining the high pressures imparted by a powered hypodermic injection device.
A further object of the invention is to provide a prefilled ampule which may be filled with a precise, known amount of medication by a medication manufacturer.
Still another object of the invention is to provide a powered hypodermic injection device which is capable of providing multiple injections.
Another object of the invention is to provide such a device which includes means for indicating the number of injections administered on a particular gas charge.